Desiccant Use in Soybean Production
One of the things that is certain in soybean farming is this: dockage at the elevator resulting from poor seed quality can significantly lower the economic value of even an exceptionally high seed yield. The following articles present results from research that was conducted to evaluate the use of harvest aids/desiccants to improve soybean harvest efficiency and quality of harvested seed.
An article titled “Impact of application volume and spray droplet size on soybean harvest aid efficacy” presents results from research that was conducted in Mississippi to determine how application parameters involved in the spraying of harvest aids/desiccants onto soybeans might affect efficacy of the applied materials. The conduct of the research and its results follow.
• The ESPS is the ideal system for soybean production in the midsouthern U.S. However, its shift toward early planting of early-maturing soybean varieties sometimes results in excessive green plant material when the crop is harvested. Thus, harvest aids are often used to mitigate this occurrence.
• Field experiments were conducted in Mississippi in 2019-2012 to evaluate the impact of application volume [5 and 20 gal./acre] and spray droplet volume mean diameter [VMD–200, 500, and 800 µm] on efficacy of three harvest aid materials [paraquat, saflufenacil, and sodium chlorate] applied to soybean.
• Efficacy of the three harvest aids was not affected by application/carrier volume.
• A VMD of 200 µm maximized both defoliation and desiccation efficacy.
• At 14 days after treatment [DAT], defoliation was 89% or above following the use of any of the harvest aids, and all three harvest aids were similar in their defoliation effect at 14 DAT.
• Defoliation efficacy following applications of saflufenacil and sodium chlorate was not sufficient prior to 14 DAT to initiate harvest.
• Sodium chlorate does have utility as a harvest aid if harvest is delayed at least 14 DAT.
• Paraquat had the greatest desiccation effect; thus, the authors concluded that any harvest aid application should include paraquat.
• Soybean seed yield was not different among the harvest aid treatments or treatment variables.
An article titled “Influence of harvest aid on soybean seed quality affected by delayed harvest and environment in Louisiana” presents results from research into how the quality of harvested soybean seed may or may not be improved by the application of a harvest aid.
• Field and growth chamber experiments were conducted in Louisiana in 2019 and 2020 to evaluate the effect of harvest aid [paraquat, sodium chlorate, or saflufenacil] application on seed quality that may be affected by inclement weather that often occurs at optimum harvest time to subsequently result in delayed harvest.
• Harvest aid application had no effect on seed quality that was affected by delayed harvest or high humidity.
• The results from this experiment indicate that soybean harvest that is delayed by more than 20 days will result in significant seed quality deterioration that will not be mitigated by harvest aid application.
Results reported in the above articles indicate that 1) efficacy of a harvest aid/desiccant applied to soybeans will not likely be affected by either the carrier volume or the size of the droplets used in its application, and 2) a harvest aid that is applied to soybean that is maturing will not improve quality of harvested seed.
Composed by Larry G. Heatherly, Jan. 2025, larryh91746@gmail.com